1. Field of the Invention
The invention relates to a pack for articles to be sterilized, comprising an optionally thermoformed plastic film forming a dome, and a paper web forming the pack base, where the paper web has been heat-sealed to the film in a peelable manner.
2. Description of the Related Art
Packs containing sterile articles are disclosed, for example, in DE 8706916 U1, which reveals that a plastic film web having thermoformed recesses is heat-sealed to a paper web in a peelable manner, the paper web being gas-permeable so that the articles can be sterilized after packing by pressure treatment with germicidal gas.
U.S. Pat. No. 4,810,541-A discloses a heat-sealable food container which is covered by a foil lid. The container as such is a thermoformed plastic moulding of a multilayer film. The inner layer of the container is conceived as a peel layer and comprises a mixture of polyethylene, ethylene-vinyl acetate copolymer and butene polymer. The foil lid is an aluminium foil coated on both sides, and the outer layer comprises polyester, the inner layer, facing the contents, comprises polyethylene. The peel layer is heat-sealed to the polyethylene layer of the lid during sealing of the container. The problem of gas sterilization of the contents is not discussed.
DE 1927746 discloses a pack for sterilized articles which comprises a plastic container with an opening, where the opening is covered by a plastic-impregnated, moisture-impermeable, germ-free paper. The synthetic resin employed for the paper impregnation is a polyacrylate, polyester or polyvinyl alcohol. The reverse of the paper is additionally provided with a polyethylene or ethylene-vinyl acetate copolymer hot-melt adhesive coating.
WO 8603976 describes a sterile pack which comprises inner and outer wrappers. The outer wrapper allows gas sterilization of the inner wrapper and the contents thereof, and subsequently the outer wrapper is heat-sealed so that the contents remain bacteria-free.
The great disadvantage of these and similar constructions of the prior art is that on opening the packs, which is generally carried out by the peel method, i.e. by peeling the plastic film off from the paper web, the plastic film tears fibres out of the paper web and thus contaminates the sterile pack contents. Thus, the constructions of the prior art do not allow a sterile pack comprising paper and plastic film to be opened in such a way that no fibres and/or fibre fragments are released.
The object of the invention is therefore to enable a gas-sterilizable pack to be opened in such a way that no fibres are torn off from the paper, i.e. the opening is carried out entirely free from fibres, although the film is peeled off by the peel method.